FR2749047A1 - PROCESS FOR ASSEMBLING TWO SHEETS USING A RIVET AND RIVET USED THEREFOR - Google Patents

Abstract

The first sheet has a hole and a counterbore having a part converging towards the front. According to the method: (a) the metal rivet has an axial rod, made of ductile fine-grained aluminum alloy, (b) the rivet head has an end face and, in front, a frustoconical section converging towards the front, (c) the shank is placed in the hole and the head in the counterbore so that the end face is substantially flush with the surface of the workpiece, the end face having an annular domed portion towards the face. rear and in axial alignment with the outer surface of the shank, (d) the side wall of the head is radially spaced from the side wall of the counterbore, the space having a volume A, (e) the domed portion has a volume B, (f) volume B exceeds volume A, so that when the bulge is flattened, the side wall of the head expands radially in volume A and pushes outward on the side wall of the head. counterbore so as to deform it radially outward, (g) a barrier material is placed between the pa side king of the rivet and the side wall of the counterbore so as to fill gaps when the side wall of the counterbore is deformed radially outwards.

Description

The present invention generally relates to the elements of

  fixation and more particularly relates to the methods of placing rivets so as to obtain a compression clamping held between two sheets, so as to prevent

  an interface displacement (friction corrosion) and to ac-

  thus increase the fatigue strength of the sheets.

  The present invention also relates to a method of

  tection and controlled riveting which prevents corrosion, in

  particular in the fixing of the outer layer of fuse-

of an airplane.

  Corrosion of rivet assemblies and around these assemblies on an aircraft has a serious influence on the life of the aircraft.

  life of the structure, preventing the airplane from reaching its

  fatigue life and its potential service life.

  The types of corrosion are mainly related to crumbling, electrolytic effect and stress. The

  There is a need for improvements to reduce or eliminate

  undermine potential corrosion problems. As will be seen, protective coatings, sealants

  and methods described herein, in common with a control of the dimensions

  rivets and holes / countersinks, can minimize or effectively eliminate

  erosion, electrolytic effect and stress in the structures

aircraft.

  There is also the need to obtain such a tightening

  kept on a uniform basis, for example in the case where a large

  number of rivets coated are used to assemble between

  the sheet metal parts, for example lap joints

  and junctions by abutting outer layers of fuse-

  the plane. There is also a need to obtain resistance to

  the fatigue of such sheets assembled together which is better

  to prevent corrosion corrosion between

the sheets.

  A main object of the invention is to apply to

  vests protective coatings and sealants which,

  at the time of installation, they can be filled with

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  wedges, bevels, bevels, out of circular countersinks, to eliminate corrosion sites of bare parts and eliminate a risk of free interval under the rivet head at the place

chamfer.

  The protective coating also serves as a barrier to prevent electrolytic corrosion, and when the coating is current-conducting it becomes electrically bonded.

  which reduces potential damage by lightning.

  The subject of the invention is a method of assembling two

  sheet metal parts using a rivet, a first sheet comprising

  both a hole, and a counterbore which is frustoconical and converges forwardly between a face of the first sheet and the hole, and towards the hole, the operations of: a) providing a metal rivet having an axially extending shaft and defining an axis, b) providing the rivet with a head having an end face and a frustoconical section converging forwardly in front of the end face, c) setting up the rod in the hole and the head in the counterbore so that the periphery of the end face of the head is substantially level with the surface of the

  piece, the end face being formed to present a part

  annular curvature protruding axially rearwardly, the curved portion being arranged to extend about the axis in substantially axial alignment with the outer surface of the rod, d) the rivet head being provided with a peripheral side wall spaced radially from a defined side wall

  by the coinage of the piece, and the space between the lateral walls

  having a volume A, e) the domed portion having a metal volume B, f) and according to which the volume B exceeds the volume A,

  so that when the curved part is flattened during a

  forming the rivet, the rivet head side wall undergoes radial expansion in volume A and pushes towards

  the outside on the side wall of the coinage of the coin

  to radially outwardly deform, g) and to provide a barrier material between the rivet side wall and the side wall of the coin counterbore.

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  to fill gaps between the side wall

  when the side wall of the work counter is deformed

radially outward.

  The invention may further include one or more of the following features: - the barrier material comprises a corrosion inhibiting agent. the corrosion inhibiting agent essentially consists of

  in an aluminized pigmented coating.

  1t) - the barrier material comprises a sealant. the part comprises two sheets and according to which the convex part is flattened during the deformation of the rivet, so

  such as shear load application areas beyond

  the expansion head of the rivet head have a thick

  which remains at least 40% of the thickness of the room in

which head is placed.

  the method comprises forming the curved portion

  in such a way that it has an annular crest portion in

  substantially axially with the outer surface of the rod, and the radially outer position of the curved portion which defines only about half of the curved portion being located in a relative arrangement axially spaced apart by

  referred to a convergent forward portion defined by the-

  said frustoconical section converging forwardly, the crest portion of the convex portion being convex rearwards in

axial radial planes.

  the end face of the head is formed in such a way as to

  lay a radially concave central recess

  3o the inside of the crest portion, the annular position

  the outermost wall up to which extends said ridge being located approximately in alignment with the surface

outer of the stem.

  - the rivet is metallic and consists of one of the following constituents: i) aluminum ii) aluminum alloy iii) titanium

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iv) titanium alloy

  v) corrosion resistant alloy (CRES).

  the barrier has a coating thickness comprised between

  be 0.000508 cm and 0.00508 cm (0.0002 and 0.002 inch).

  the deformation of the rivet forces the material of

  barrier on the side wall of the coin counter.

  the process comprises coating the bar material with

  on the annular curved part and comprising a flattened

  the domed part so as to penetrate the material

  Barrier, located on the latter, in metallic interstices.

  located on the surface of the flattened curved portion and in a manner adjacent to the outermost position up to which extends the side wall of the undercut head

  radial expansion, during said radial expansion of the

lateral king of head.

  the method also comprises a coating of the barrier material on the frustoconical section converging towards the front, the flattening of the convex part penetrating the barrier material, located on the frustoconical section, in

  metallic interstices of the frustoconical chamfer of the first

  sheet metal, and in a manner adjacent to the most

  up to which extends the side wall of the head

having undergone radial expansion.

  The invention also relates to a metal rivet

  having a head defining an annular domed portion on the top of the head, and a barrier solid material coating the rivet to fill gaps at the rivet head walls and the coin counterbore, where the annular curved portion is flattened during deformation

3o of the rivet.

  The invention also relates to a method for clamping together two sheet metal parts using a rivet, a first sheet having a hole, and a counterbore which is

  frustoconical and converges forward between a face of the first

  first sheet and the hole, and towards the hole, the operations consist

  both: a) providing a metal rivet having an axially extending shaft defining an axis, the metal of the rivet

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  consisting essentially of an aluminum alloy

  fine-grained tile, b) providing the rivet with a head having an end face and a frustoconical section converging forwardly in front of the end face,

  (c) to put the rod in the hole, with a

  head in the countersink so that the periphery of the end face of the head is above the surface of the

  piece, the end face being formed to present a part

  IU annular convex ring protruding axially upwards, the convex portion being arranged to extend about the axis in a substantially axial alignment with the outer surface of the rod, the annular curved portion forming a recessed portion the d) the rivet head being provided with a peripheral side wall spaced radially from a defined side wall

  by the counterbore of the workpiece, the rivet rod presenting an

  terminal end, e) applying a force to the annular curved portion and to the terminal end so as to expand the rod in the vicinity of the terminal end and to bring it into contact with the exposed outer surface of the lower plate, and at the same time cause a flattening of the

  annular rounded part, and to push up the

  fine-grain aluminum alloy of the rod so as to achieve a metal creep upwards and in a central position towards the recessed part, f) the application of the force being continued so as to form at the bottom end, having been expanded, an anchor tail at a position adjacent the outer surface of the bottom plate by exerting a clamping force on that outer surface, and producing a surface upper flattened on the rivet head, said upper surface being lowered towards the level of the upper surface of the upper sheet, but spaced above this level, so that the two sheets are kept in a tight state force between the head and the

  anchor tail, once the training is completed.

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  The invention may further comprise one or more of the following features: - the flattened upper surface of the head is deformed

  to be between 0 and 0.01524 cm (0.006 inches)

  above the upper surface of the upper sheet. - the fine-grained metal of the rod is forced to flow upwards so as to fill the recessed part when the

  annular curved portion is flattened so as to be

  above the upper surface of the upper sheet, and the anchor tail is formed by applying a force, the

  it is also characterized by a high elongation.

  the metal of the rivet has a fine fine grain size

  taken between 5 and 9, the grain size being determined by

ASTM E: 112.

  the method comprises providing the sheets so that they consist essentially of a metal chosen from the group of aluminum, titanium, stainless alloys and

combinations of alloys.

  the rivet metal is filled in the recessed portion of the stem so as to lock the rivet head against a radially inward contraction,

  so that the tight state is maintained.

  the aluminum alloy is chosen from the group which comprises:

2017-T4

2024-T4

2117-T4

2219-T62

7050-T73

7050-T715.

  the rivet is formed from an aluminum alloy wire selected from the group of the following table, the selected wire having a grain size and physical characteristics as presented in the following table:

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  Alloy Diameter Elongation Resistance to Size & Annealing in cm in 5.08 cm shear grain (inches) (2 inches) Min. Max. minimum minimum% l0b Pa l0b Pa ASTM E: 112 (kpc) (kpc)

  2017-T4 0.23368 to 0.14351 14 241.15 282.49 7

(0.092 to 0.565) (35) (41)

  2024-T4 0.23368 to 0.14351 13 254.93 n / a 6

1) (0.092 to 0.565) (37)

  2117-T4 0.23368 to 0.14351 18 179.14 nd 5

(0.092 to 0.565) (26)

  2219-T62 0.23368 to 0.14351 12 206.7 nd 5

(0.092 to 0.565) (30)

  7050-T73 0.23368 to 0.14351 14 282.49 316.94 5

(0.092 to 0.565) (41) (46)

  7050-T715 0.23368 to 0.14351 15 241.15 282.49 5

(0.092 to 0.565) (35) (41)

  nd = not available (kpc = kilopond-force per square inch) - rivet metal is deformed upward on the inside of the shank below the counterbore and in the direction

  said head-back portion to cause an expansion of

  rivet and fill the recessed part when the tail

anchor is formed.

  Another object of the invention is to coat the barrier on the rivet side wall prior to the deformation of the rivet, and this with a variation in thickness of about

  0.00508 cm to 0.01524 cm (0.0002 to 0.006 inches). Such a ma-

  may be a sealant or an anti-corrosive material

  erosion, or a combination of a barrier coating and a

  sealant. A deformation of the rivet head

  Forcibly pushing the barrier material onto the wall

  side of the counterbore of the workpiece, and in the metal interstices

lic.

  Another object of the invention is to provide a coating

  barrier on the annular curved part of the rivet, so that a flattening of the convex part penetrates the

  barrier material in the metal interstices to the over-

  face of the flattened convex portion and in a manner adjacent to

  the outermost position up to which the

  lateral king of the head having undergone a radial expansion,

  the radial expansion of the side wall of the head.

  These objects and advantages of the invention, as well as

  others and as well as the details of an embodiment it-

  lustrative, will be better understood from the following description

and drawings including:

  FIG. 1 is a sectional elevational view illustrating

  as a rivet inserted in a room,

  FIG. 2 is a view similar to FIG.

  presenting the rivet during crush deformation,

  FIG. 2a is a view similar to FIG.

  presenting the rivet after complete deformation, an anchor tail having been formed, FIG. 3 is a sectional view, partial and on a larger scale, showing a rivet head having a first (minimum) dimension ratio vis-à- screw of a coin counter,

  FIG. 4 is a view similar to FIG.

  as a rivet head having another aspect ratio (maximum) with respect to a coin counter, FIG. 5 is an exploded view showing the parts

  of a rivet in relation to the parts of a hole and a la-

  6a is a sectional view on a larger scale showing an initial support of a rivet in sheet metal parts, FIG. 6b is similar to FIG. 6a, but represents the position of the rivet and plates after depression of the rivet,

  3o) Figs. 7 (a) - (e) are views showing

  5 is a sectional view on a larger scale showing the barrier material on the rivet, FIG. 9 is similar to FIG. 8, but represents the positioning, FIG. is an even larger sectional view

  scale representing the barrier material in the intersti-

  these occurring in the walls of the rivet and the piece,

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  Fig. 11 is a view showing a free gap when the barrier material is not used and Fig. 12 is a sectional view, partial and at most

  large scale, representing the deformation of the barrier at the point of the ridge in elevation of the head, after deforma-

  tion. In FIG. 1, two panels 111 and 112 (metal, fiberglass, composites, etc.) constitute part 110. A main hole 113 extends in the two panels and a countersink 209 1 (and a converging chamfer 114 in the panel 111. The hole and

  the chamfer have a common axis 116 extending forwardly.

  The fine-grain ductile aluminum alloy rivet 118 has an axially extending rod 119 inserted forwardly through and through the hole 113 with clearance as indicated. The rivet stem or shank protrudes forward of the panel 112. The rivet head 120 has an end face 121 (forming an annular curved portion) which is rearwardly facing and spaced above the upper surface. of the panel 111. A cylindrical section 208 of the rivet is delimited by the cylindrical wall 209; and a frustoconical section 122 of the rivet, converging forwards, is spaced apart

from section 208 forward.

  The rivet is progressively deformed, for example by means of a crushing machine or by means of hammers 124 and 125 so as to flatten the protruding crown portion 121a and to simultaneously form the driven part or anchor piece 126 shown in Figure 2a. The arrows on the cross section of the head 120 indicate the directions of metal deformation during flattening of the domed portion 0. In this regard, the metal of the head adjacent the converging surface 122a tends to flow toward the annular edge 130 at the intersection of the hole 113 with the chamfer 114 and around this edge, due to the fact that the force imparted to the rivet head by the deformation is directed to the central position 3 through the crest of the annular curved portion to the edge 130 by defining an annular extrusion surface of

  convex way for a creep of the rivet metal on top.

  The rivet, as shown in FIG.

  the annular aperture 121a of the end face 121 which is sensi-

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  level with the room surface 131; in addition, the end face forms an annular curved portion 132 which protrudes axially rearwardly. This curved portion is generally annular and extends around the axis 116. The extent of the protrusion of the curved rearward portion is such that the entire end face 121 extends (prior to the deformation) substantially above and parallel to the workpiece surface. Once the deformation of the rivet is completed, as indicated in 121b in Figure 2a, the domed portion is substantially eliminated. The end face 121 then protrudes above the level of the workpiece surface 131 by 0.001 to 0.006 inches (0.00254 to 0.01524 cm).

  The curved, annular portion is located radially

  behind the chamfer 114, so that the material of the rivet head remains in contact with the chamfer and does not form a game with it under the effect of a flattening of the curved portion. For best results, the radially outer position 132a along which the curved portion extends, which

  flares outwards and towards the front, is located

  entirely in an axially spaced arrangement

  with respect to the chamfer, more precisely the chamfer conver-

  114. The flare located at 132a, towards the outermost periphery of the head, is at an angle adjusted to give

  the assurance that its outer periphery is in a normal

  In addition, the ridge portion 132b of the curved portion is disposed in substantially axial alignment with the outer surface of the shank 119b and also with the hole.

  113. The height "d" (see Figure 3) of the ridge above

  above the level of 121a is between 0.01016 and 0, 04064

  cm (0.004 and 0.016 inches), for best results.

  Therefore, during the riveting process, the over-

  convergent face 122a of the rivet head remains, on sensitive-

  entire length, resting on the chamfer 114 and there is no springback to a point such that a game is

  would once form the establishment completed.

  In this respect, it should be noted that the concavity or part thereof

  central line of the rear face of the head which is located at 133 in Figure 3 fills during the deformation of the head

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  of rivet, that is to say the flattening of the curved portion

  nular, and by reflux filling of the stem material when the stem column crushes and an expansion occurs.

  product. The deformation forces, indicated by the arrows in FIG. 2, remain concentrated in alignment with the

  brake 114, so that the metal of the head is constantly re-

  pushed in a forced way towards the chamfer in order to prevent the development of games. The uniformity of the complete filling of recessed portions 133 located in multiple rivets

  Now the sheets clamped together are obtained by using

  of a fine-grained ductile aluminum alloy, such as

as indicated below.

  As riveting progresses, the metal of the head delimits

  Moved by the head wall 209 and located between the domed portion 132 and the section 122 is typically deformed toward the chamfer

  209 (see FIG. 3) so as to complete the annular game.

  lar. In actual practice, with regard to the production of rivets and for best results, when the domed portion is flattened during the deformation of the rivet, the wall

  side of the rivet head is being expanded

  and pushes outward on the side wall of the chan-

  piece brake so as to deform the latter radially outwards.

  Figure 3 illustrates the ratio of a head diameter of

  nimal (at 209) at a maximum counterbeam (at 210), so that the rivet head abuts forwardly at 114, as shown; and FIG. 4 illustrates the ratio of a maximum head diameter (at 209) to a minimum countersink (at 210), so that (3) the rivet head bears backward in such a way that the curved portion 132 protrudes rearward on

  the room, before a deformation.

  During a deformation, the counterbore 210 is radially outwardly expanded under the effect of

  the expansion of the wall 209, when the curved portion is flattened

  tie. The desired deformation of the convex portion 132 will occur

  during riveting, so as to maintain the walls 209 and 210 in radial compression and in peripheral tension, of the

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  desired way. In addition, an anchor tail is

  in the manner described herein to create a clamp.

  In both FIGS. 3 and 4, the metal of the fine-grained aluminum rod is extruded upwards (see arrow 400) so as to fill the recessed portion delimited by the annular curved portion, during the flattening of the domed portion, and the top of the rivet head remains above

  (that is, behind) the plane of the workpiece surface 131.

  Typically, the metal of the rivet (which is preferably a fine-grained aluminum alloy to increase metal creep at 400) is softer than the metal of the workpiece. For example, the work panel has a tensile strength substantially exceeding

  the tensile strength of the rivet, for better results.

  States. Thus, the rivet and the piece will be the subject of an ex-

  pansion and contraction at rates to prevent

  radial intervals during a temperature change.

  In a typical example, the maximum diameter of the head is in the range of 0.65532 to 0.65024 cm (0.258 to 0.256 inches), and the side wall of the head has a length

  axial about 0.03048 to 0.10668 cm (0.012 to 0.042 inches).

* Furthermore, the length of the side wall increased by the

  The axial length of the head converging towards the stem is

  taken in the range of 0.05588 to 0.26416 cm (0.022 to 0.104 inches).

  If we refer to Figure 5 below, it is analogous

  shown in Figure 3, but represents the exploded axial

  is lying. Games are shown between the wall 209 and the counterbore 210, such as that which exists during the insertion of the rivet 3o (but prior to the deformation), and between the rod 119a and the hole 113. Furthermore, only for the purposes of a better identification, a slight axial separation is represented between the convergent seat 122a and the convergent surface of

  head 114 (angle of convergence of 120 as shown in FIG.

  1) and between the convex edge 130 and the outer surface

  concave 223 of the transition section 220.

  The volumes of the cylindrical section 208, the frustoconical section 122 and the transition section 220 are adjusted, or prefixed, with respect to the dimensions of the diameter of the borehole.

13 2749047

  piece 113 and the dimensions (axial and radial) of the chamfer piece 114 and countersink 210, so that, during the flattening of the curved portion during the deformation of the rivet, the domed portion has a flattened surface which is located between limits defined as being approximately - flush with the outer surface of the workpiece - protruding 0.01524 cm (0.006 inch) from the

outer surface of the room.

  This ensures aerodynamic behavior and is ensured by the use of the fine-grain aluminum alloy of the rivet, so as to obtain a desired metal cloud,

the manner described.

  Another important aspect consists in defining and maintaining two radii R 1 and R 2, such that R 2 is between 95% and 75% of R 1 (difference of 5% - 25%) for which: R 1 is the radius of the concave surface 223 in radial axial planes (the surface 223 being annular) - R2 is the radius of the convex work surface 130, in radial axial planes, the surface 130 being annular and receiving the sliding contact of the surface 223 when of the

deformation of the rivet.

  When these relations are maintained, together with the convergent angular shape of the surfaces 114 and 122a of the

  shown (the surface 114 intersecting the surface 130 and the surface 122a intersecting the surface 223), the support support

  the rivet shear is made optimal, while the

  city of tension in tension of the rivet is ensured. This advantage is obtained even in the case of an installation in the thinnest sheet possible (that is to say a situation practically knife edge), the areas 300 and 301 (Figure 2) around the rivet head remain constant, ensuring a high degree (40% minimum of the sheet) shear bearing area of the sheet. Figure 5 also shows the annular crest portion

  132b as being situated between radially

  upper and outer (see lines 260 and 261 parallel to the axis 116), the radial gap 262 between the lines 260 and 261 being less than 25% of the radial dimension 264 of the section

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  cross section of the convex part, the interval being in

  the alignment of the outer surface of the rod.

  A comparison of FIGS. 6a and 6b shows that, during deformation of the rivet, the head wall 209 moves radially outward (to the left) so as to contact the hole wall 210; and the wall 209 causes an additional displacement of the wall 210 to the left by a value Sl, the final wall positions being indicated at 209 'and 210'. At the same time, the rod wall 223 moves

  [0 radially outward (to the left) and comes to

  tact of the hole wall 113; and the wall 223 causes a

  further placing the wall 113 to the left by an approximate value S2, the final wall positions being indicated by 223 'and 113'. In fact, the wall 223 'is oriented at an angle α to its initial position 223, the wall 223' flaring along the direction 240. As described below, an "anchor tail" is formed at the end portion of the rod, hooking the edge of the hole in the workpiece, such that equal clamping forces are produced between the anchor tail and the leading angular portion. In addition, in FIG. 6a, the metal of the rivet is moved (see arrow 241) towards the recessed portion

  around which the domed portion 132 extends,

  to fill this recessed portion, when the annular curved portion is flattened, and the flattened top or rear surface 403 is held above the level of the sheet surface 431. See also the annular head portion 432 formed by

  the periphery of the head above extending to the over-

  adjacent face 431, maintaining the head surface 403 above) of the level of 431. As a result the deformed rivet locks

  the sheet metal parts 111 and 112 in a tight state between them.

  See arrows 420 and 421 in Figure 2.

  For best results, the rivet is formed from a fine-grained aluminum alloy wire selected from the group of the following table, the selected wire having a grain size and physical characteristics as shown in the following table :

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  Alloy Diameter Elongation Resistance to Size & Annealing in cm in 5.08 cm shear grain (inches) (2 inches) Min. Max. minimum minimum% 10 Pa 10 'Pa ASTM E: 112 (kpc) (kpc)

  2017-T4 0.23368 to 0.14351 14 241.15 282.49 7

(0.092 to 0.565) (35) (41)

  2024-T4 0.23368 to 0.14351 13 254.93 n / a 6

(0.092 to 0.565) (37)

  2117-T4 0.23368 to 0.14351 18 179.14 nd 5

(0.092 to 0.565) (26)

  2219-T62 0.23368 to 0.14351 12 206.7 nd 5

(0.092 to 0.565) (30)

  7050-T73 0.23368 to 0.14351 14 282.49 316.94 5

(0.092 to 0.565) (41) (46)

  7050-T715 0.23368 to 0.14351 15 241.15 282.49 5

(0.092 to 0.565) (35) (41)

  nd = not available (kpc = kilopond-force per square inch)

  In this respect, the grain size number is a function

  reverse the actual grain size and is measured against

  according to ASTM E: 112. The grain size numbers are

  to those that could previously be obtained, so that

  smaller grains are now made possible, leading to

  to a significantly increased ability to creep

  killed in the stem to fill the recessed portion surrounded by the annular curved portion. This in turn allows a better uniformity of the deformation of multiple rivets so as to keep the sheets in a tight state maintained,

  i.e. for reduced friction corrosion.

  In the table, "elongation" refers to a measured separation of benchmarks for a sample during a tensile test, to failure. Previous values

  lengthening to 11 or 12 are exceeded by using

  a fine-grain aluminum alloy, which improves ductility to promote creep from the rod metal to the

  recessed part to be filled. Therefore, the

  rivet metal is characterized by high elongation.

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  Moreover, the expansion of the rod in the vicinity of the outer surface of the lower sheet metal part causes contact

  with this sheet metal which is such that it facilitates the

  ducting a clamping force when the anchor tail is formed. The views (a) to (e) of FIG. 7 represent a typical example of deformation of the present rivet. The rivet 120 having the form shown is inserted into the structure consisting of two sheets 111 and 112, or two metal materials having the composition mentioned, with the holes and counterbores prepared within the limits of determined tolerances. The riveting tool is used to apply a force to the rivet head 120 "annular curved portion" and simultaneously also on the end

  terminal 118a. It will be noted that the crest of the annular curved portion

  nular is spaced approximately 0.0254 cm (0.010 inch) above

  of the workpiece surface 131, on the view 7 (a).

  As shown in Fig. 7 (b), as the crushing force increases, the rivet pin 118 begins to swell to form a converging or annular corner region at 118b, below the surface. lower part 112a. The wider position 118c up to which the rod extends is in axial alignment with the head 120. The

  annular curved portion 132 is flattened simultaneously.

  In Fig. 7 (b), the bump portion ridge has been flattened at a spacing of about 0.02032 cm (0.008 inches) from the workpiece surface 131; and the lower surface 132a of the concave recessed portion has been pushed up to a level of about 0.00762 cm (0.003 inch) from the level of the upper work surface 131. This corresponds to a filling by repressing the recessed part. By

  moreover, the creation of a tightening begins, as indicated below.

  after. Figure 7 (c) shows the level of the curved crown ridge reduced to about 0.01905 cm (0.0075 inches) from the surface 131, and the lower recessed portion surface s5 132a pushed upwardly. to a level of about 0.01397

  cm (0.0055 inch) from the work surface.

  With the continued application of the crushing force, the shank 118d is deformed, as in Figure 7 (d), to come into contact, hanging or flat,

17 2749047

  at 118c, from the bottom part surface 112a, around the hole 113, creating a compressive clamping pressure to the flared bottom face 120 of the head 120. Note that the flattened annular crown portion is reduced at a level of about 0.01778 cm (0.007 inches) from the workpiece surface, and the lower surface 132a of the recess is now raised to about 0.01651 cm (0.0065

  inch) relative to this surface.

  When a larger crushing force is applied, the rod 118 is deformed so as to provide an "anchor tail" shape, adjacent the bottom face 112a of the workpiece, as shown in FIG. (e). The party crest

  curved ring and the bottom of the recessed part are now

  but at the same spacing, 0.0127 cm (0.005 inch), relative to the work surface, as shown, so that the head is now flattened. Such deformation in opposite directions of the crest of the annular curved portion (downward) and the

  concave recessed portion 132a (upwardly), which is easily

  by the fine-grained metal composition of the metal of the

  vet, further facilitates a desired uniform deformation of

  vets to the state shown in Figure 7 (e), with a

  rage maintained sheet metal parts. Such tightening increases the

  resistance to seal fatigue, and hermetically sealed

  sealingly prevents the development of cor-

erosion at the interfaces of the parts.

  For example, the grain size is linked to the nominal inches

  grain averages per grain, for a total of 50 interceptions, and at an average interception distance, according to the following table: Size cm (inches) Distance Distan rial in cm (pe) nominal grain size intercept per 2.54 cm average means: cm (per l paxcs) for 50 / grain (inch) interceptions

5. 0.00635 0.0056642 0.28321

(0.0025) (0.00223) (0.1115)

, 5 0.00508 0.0047498 0.23749

(0.0020) (0.00187) (0.0935)

18 2749047

  Table (continued) Size cm (inches) Distance Minimum nominal grain intercept distance per 2.54 cm average means: cm (inch) for 50 / grain (inch) interceptions

0.004572 0.0039878 0.19939

(0.0018) (0.00157) (0.0785)

6.5 0.003556 0.0033528 0.16764

(0.0014) (0.00132) (0.0660)

7 0.003048 0.0028194 0.14097

(0.0012) (0.00111) (0.0555)

7.5 0.00254 0.0023876 0.1938

(0.0010) (0.000940) (0.0470)

8 0.002286 0.0199898 0.099949

(0.0009) (0.000787) (0.03935)

8.5 0.001778 0.0016814 0.084074

(0.0007) (0.000662) (0.03310)

9 0.001524 0.0014147 0.070739

(0.0006) (0.000557) (0.02785)

RULES:

  1. Penetrations into a grain in the direction of the test line are counted as half (1/2) of the

grains.

  2. Do not count the ends of the test line

as an interception.

  3. A grain extending in the line will be counted as one

(1) grain.

  4. Two (2) or more grain junctions extending in a line shall be counted as one and one-half grains

(1-1 / 2).

  5. Two (2) interceptions with the same grain will be counted

two (2) total.

  A determination of the grain size in a wire

  sample from which rivets of the invention

  to be formed, involves for example counting 50 successive grains (i.e., a prefixed number of grains) (at 100x magnification) along a straight path across

192749047

  the end face of a sheared wire, and to determine the length dimension, that is, the distance occupied by the

  grains, then divide this distance by 50 so as to de-

  end an average intercept distance. This distance is related to the average nominal inches / grain and the grain size, as referenced here, as shown in FIG.

table above.

  As indicated here, a wire sample is usable for the rivet only, if the determined fine grain size is between 5 and 9, which means that the distance

  determined average interception (as determined by

  so, above) is between 0,0056642 cm (0.00223 inches)

and 0.0014147 cm (0.000557 inches).

  Another object of the process of the invention is to allow the formation of a larger anchor tail diameter, such as

  than the initial stem diameter of the rivet, during the deformation

  the rivet to the set up. Such formation is permitted by the use of the fine-grained aluminum alloy described herein. For example, the anchor tail can now be formed to have a minimum diameter that

  is at least 1.4 times the initial diameter of the undistorted stem

  for a finished rivet. In another example, a 7050-T73 alloy is shaped to have a minimum anchor diameter diameter that is at least 1.5 times the initial shank diameter. This value is to be compared to an anchor shank diameter of about 1.3 times the initial shank diameter for anterior rivet materials. Large anchoring tails facilitate better the maintained clamping, the advantages being

described above.

  } If we turn now to Figure 8, it represents

  a rivet 118 having a thin barrier material 400 on its surfaces, for example 400a on the end face 121 of the annular curved portion 121a, 400b on the outermost head wall 209 and 400c on the frustoconical surface or

  convergent 122a. Barrier thickness is typically

  between 0.000508 cm and 0.00508 cm (0.0002 and 0.002 inches);

  and the protective barrier typically consists of a

  sealing, or a coating, or a product

  sealing applied over a coating.

2749047

  As an example, the coating may consist of

  aluminized particles in a support, such as a phenolic resin

  baked on rivet surfaces at temperatures

  its between 200 and 450 F, so as to volatilize the support.

  An example of trading is TecKote 8-G or HI-COTE 1.

  An example of a sealant is a rubber

  Flexible epoxy lysulfide in a sprayable solution. A

  example of the trade is the PRC1436GE2 of Courtauld.

  Fig. 9 shows the barrier material layer 1) 400b displaced outwardly during an expansion of the head to the coin counterbore wall 210 and into this wall,

  that is to say in the interstices present on this wall.

  Figure 10 is a view with a very large magnification

  wherein the surface roughness 209a and 210a on the walls 209 and 210 form interstices in which the barrier material 400b penetrates, as shown. Note the variable thickness and the tooth configuration of

  saw of the material 400b filling the interstices and

hermetically.

  It will also be noted that the flattening of the curved portion causes an extrusion of the barrier material so as to

  form a 400d cover extending over the workpiece, in

  adjacent to the edge of the coin hole, with a

  additional hermetic closure. Barrier layers

  400a and 400b can advantageously extend until

couvrement.

  FIG. 9 also shows the 400c barrier layer

  pushing on the converging chamfer 114a of the sheet metal part 111, so as to fill the interstices. This eliminates 3 (0 the free interval 410 as formed in previous implementations, as in FIG.

  sealing or coating is used, as in the pre-

this invention.

  In Figure 8, the volume of the curved portion 121a may have a value A; the space separating the walls 209 and 210 may have a volume B; and the volumes are such that when the curved portion is flattened during deformation, the wall 209 is expanded in volume A and pushed towards

21 2749047

  the outside on the side wall 210 so as to deform

outwards.

  In addition, the following relationships are maintained: h) the ratio B / A is in the range of 1.20: 1 to: 1,

  i) the leading end face is formed so as to de-

  finish an indented portion delimited by the annular curved portion

nular and

  j) the flattening of the curved part is executed by

  1 that the shear load application areas above

  the expansion head of the rivet head have a thick

  which remains at least 40% of the thickness of the piece of sheet metal

in which the head is located.

  On the other hand, A and B have one of two relationships: xi A is in the range of 0.000196 cm3 and 0.0031135 cubic centimeter (0.0000120 cubic inch and 0.000190 cubic inch); and B is expected to be in the range of 0.0002044 cm3 and 0.0147482 cm3 (0.000005 cubic inch and 0.00090 cubic inch), x2 A is in the range of 0.00002130318 cm3 and 0.000213018 cm3 (0.0000013 cubic inches and 0.000013 cubic inches); and wherein B is in the range of 0.000475224 cm3 and

  0.0144205 cm3 (0.000029 cubic inches and 0.00088 cubic inches).

  In addition, A is expected to be in the range of 0.000196 cm3 and 0.0031135 cm3 (0.0000120 cubic inch and 0.000190 cubic inch); and B is provided to be in the range of 0.000204838 cm3 and 0.0147482 cm3 (0.0000125 cubic inches and 0.00090 cubic inches). Typically, the maximum head diameter is in the range of 0.30734 cm to 1.32334 cm.

  (0.121 to 0.521 inches), and the leading side wall has a length

  axial thickness of about 0.03048 cm to 0.10668 cm (about 0.012 to

0.042 inches).

  The method comprises forming the domed portion of

  to have an annular crest portion in substantially

  sibly axial with the outer stem surface, and the posi-

  radially outer to which extends the domed portion which defines only about half of the domed portion being located in a relative axial arrangement

22 2749047

  spaced apart from a converging front portion defined by the frustoconical section converging forwardly, the crest portion of the convex portion being convex rearwardly in axial radial planes. The outermost annular position up to which the ridge extends is approximately in alignment with the outer surface of the shank. The rivet and the wall are both metallic, the metal of the rivet being softer than the metal of the wall, and the rivet consists of one of the following constituents: bi) aluminum ii) aluminum alloy iii) iv titanium ) titanium alloy

  v) corrosion resistant alloy (CRES).

23 2749047

Claims (22)

  1. Method for assembling two sheet metal parts using   a rivet, a first sheet with a hole, and a la-   mage who is frustoconical and converges forward between a   face of the first sheet and the hole, and towards the hole, the   rations comprising: a) providing a metal rivet having an axially extending shaft defining an axis; b) providing the rivet with a head having an end face and a frustoconical section converging forwards forwardly forwardly; end face, c) to place the rod in the hole and the head in the counterbore so that the periphery of the end face of the head is substantially level with the surface of the   piece, the end face being formed to present a   annular curvature protruding axially rearwardly, the curved portion being arranged to extend about the axis in substantially axial alignment with the outer surface of the rod, d) the rivet head being provided with a peripheral side wall spaced radially from a defined side wall   by the coinage of the piece, and the space between the lateral walls   having a volume A, e) the domed portion having a metal volume B, f) and according to which the volume B exceeds the volume A,   so that when the curved part is flattened during a   forming the rivet, the rivet head side wall undergoes 3o radial expansion in volume A and pushes towards   the outside on the side wall of the coinage of the coin   radially outwardly, g) and providing a barrier material between the rivet side wall and the side wall of the work counterbore so as to fill gaps between the side wall when the side wall coin counterfeiting is distorted radially outward.   2. The process of claim 1 wherein   barrier material comprises a corrosion inhibiting agent. 24 2749047   The process according to claim 2, wherein the corrosion inhibiting agent consists essentially of a aluminized pigmented coating.   4. The process of claim 1 or 2 wherein   the barrier material comprises a sealant.   5. A method according to claim 1, wherein the part comprises two sheets and wherein the domed portion is flattened during the deformation of the rivet, such that the shear load application areas around the rivet head having undergone the expansion has a thickness that remains at least 40% of the thickness of the room in which the head is placed. The method of claim 1 including forming the bulged portion to have an annular ridge portion in substantially axial alignment with the outer surface of the stem, and the radially outer position of the curved portion that defines that about half of the domed portion being located according to a provision   relatively axially spaced relative to a convergent part   forward direction defined by said conical section   vergeant forward, the crest portion of the domed portion   being convex backward in axial radial planes.   The method of claim 6, wherein the leading end face is formed to have a concave central recess portion radially inwardly of the ridge portion, the outermost annular position at which said ridge extends approximately in alignment with the outer surface of the stem.   3 ( 8. A method according to claim 1, wherein the rivet is metallic and consists of one of the following constituents: i) aluminum ii) aluminum alloy iii) titanium iv) titanium alloy   v) corrosion resistant alloy (CRES). 2749047   9. The method of claim 1, wherein the barrier has a coating thickness of 0.000508.   cm and 0.00508 cm (0.0002 and 0.002 inches).   The method of claim 9, wherein the deformation of the rivet forces the barrier material by force.   on the side wall of the coin counter.   11. The process of claim 1 comprising a recipe   clothing of the barrier material on the rounded annular   and comprising a flattening of the domed portion of   to penetrate the barrier material, located on this   ci, in metal interstices located on the surface of the flattened curved portion and in a manner adjacent to the outermost position to which the side wall extends   radial expansion of the head, during the said ex-   radial pansion of the head side wall.   The process of claim 10 further comprising   a coating of the barrier material on the truncated section   converging forward, the flattening of the convex portion of the barrier material, located on the   frustoconical section, in metallic interstices of the chan-   frustoconical brake of the first sheet, and in a manner adjacent to the innermost position up to which extends the   lateral wall of the head having undergone radial expansion.   13. Metal rivet having a head defining a   annular rounded portion on the top of the head, and a   sturdy barrier material covering the rivet so as to fill   interstices located at the walls of the head of ri   vet and coin counterbore, when the annular curved part   is flattened during the deformation of the rivet.   14. A method of clamping together two sheet metal parts using a rivet, a first sheet having a hole, and a counterbore which is frustoconical and converges forwardly between a face of the first sheet and the hole, and towards the hole, the operations of: a) providing a metal rivet having an axially extending shaft defining an axis, the metal of the rivet   consisting essentially of an aluminum alloy fine-grained tile, 26 2749047   b) providing the rivet with a head having an end face and a frustoconical section converging forwardly in front of the end face,   (c) to put the rod in the hole, with a   head in the countersink so that the periphery of the end face of the head is above the surface of the   piece, the end face being formed to present a part   annular curved section projecting axially upwardly, the curved portion being arranged to extend about the axis in a substantially axial alignment with the outer surface of the shaft, the annular curved portion forming a central recess portion; (d) the rivet head being provided with a peripheral side wall spaced radially from a defined side wall   by the counterbore of the workpiece, the rivet rod presenting an   terminal end, e) applying a force to the annular curved portion and to the terminal end so as to expand the rod in the vicinity of the terminal end and to bring it into contact with the exposed outer surface of the lower plate, and at the same time cause a flattening of the   annular rounded part, and to push up the   fine-grain aluminum alloy of the rod so as to achieve a metal creep upwards and in a central position towards the recessed part, f) the application of the force being continued so as to form at the bottom end, having been expanded, an anchor tail at a position adjacent the outer surface of the bottom plate by exerting a clamping force on that outer surface, and producing a surface upper flattened on the rivet head, said upper surface being lowered towards the level of the upper surface of the upper sheet, but spaced above this level, so that the two sheets are kept in a tight state force between the head and the   anchor tail, once the training is completed.   The method of claim 14, wherein the flattened upper surface of the head is deformed so as to 2749047   be between 0 and 0.01524 cm (0.006 inches) above the   upper surface of the upper sheet.   16. The method of claim 14 wherein the fine-grained metal of the stem is forced to flow upwardly.   in order to fill the indented part when the bom-   annular bezel is flattened so as to be above the upper surface of the upper sheet, and the anchor tail is formed by applying a force, the metal   also being characterized by high elongation.   1) The method of claim 14 wherein the rivet metal has a fine grain size of between 9 and 9, the grain size being determined by ASTM E: 112. 18. The process of claim 14 comprising the   supply of sheets so that they consist essentially of   a metal chosen from the group of aluminum,   tane, stainless alloys and combinations of alloys.   19. A method according to claim 14, wherein the metal of the rivet is filled in the   removing the rod so as to lock the rivet head   be a contraction radially inwards, so that the tight state is maintained.   The method of claim 14, wherein the aluminum alloy is selected from the group consisting of: 2017-T4 2024-T4 2117-T4 2219-T62 7050-T73 7050-T715.   21. A method according to claim 14, wherein the rivet is formed from an aluminum alloy wire selected from the group of the following table, the selected wire having a grain size and physical characteristics as presented in the next board: 28 2749047   Alloy Diameter Elongation Resistance to Size & Annealing in cm in 5.08 cm shear grain (inches) (2 inches) Min. Max. minimum minimum% 106 Pa 10o Pa ASTM E: 112 z (kpc) (kpc)   2017-T4 0.23368 to 0.14351 14 241.15 282.49 7 (0.092 to 0.565) (35) (41)   2024-T4 0.23368 to 0.14351 13 254.93 n / a 6 1 ((0.092 to 0.565) (37)   2117-T4 0.23368 to 0.14351 18 179.14 nd 5 (0.092 to 0.565) (26)   2219-T62 0.23368 to 0.14351 12 206.7 nd 5 (0.092 to 0.565) (30)   7050-T73 0.23368 to 0.14351 14 282.49 316.94 5 (0.092 to 0.565) (41) (46)   7050-T715 0.23368 to 0.14351 15 241.15 282.49 5 (0.092 to 0.565) (35) (41)   nd = not available (kpc = kilopond-force per square inch)   22. Process according to any one of claims 1   at 12 and 14 to 21, wherein rivet metal is deformed upwardly within the rod below said counterbore   and in the direction of the said head-back portion for provoking   expand the rivet and fill the recess   when the anchor tail is formed. 3 ()